Spoon your way to a leaner physique by eating this mix of cereal, yogurt, and blueberries. Researchers at Penn State University found that subjects who ate a low-calorie diet with carbs coming only from whole grains lost significantly more abdominal fat than those following a low-calorie diet with carbs from refined sources, such as white breads and pastas. Greek yogurt is an excellent source of protein. On average it has 18 grams of protein, plus it is low in calories and lactose (making it easy to digest, if you are someone who is sensitive to dairy). Blueberries are high in fiber and antioxidants.